Embodiments relate to subterranean operations and, in some embodiments, to introduction of fluids comprising kiln dust into a wellbore through a bottom hole assembly.
Wells are generally drilled into the ground to recover natural deposits of hydrocarbons and other desirable materials trapped in geological formations in the Earth's crust. Wells may be drilled by rotating a drill bit which is located on a bottom hole assembly at a distal end of a drill string. In conventional drilling, a wellbore is drilled to a desired depth and then the wellbore is lined with a larger-diameter pipe, typically referred to as a casing. Prior to inserting the casing and cementing it in place, the drill string and drill bit are removed from the wellbore. After the casing has been cemented in place, drilling is continued. In some instances, a technique referred to as “casing drilling” is used in which a casing is used in place of a drilling string. Similar to a drill string, the drill bit is connected to a distal end of the casing, and the casing is used to transmit rotational and axial forces to the drill bit. When the wellbore has been drilled to a desired depth, the casing may be cemented in place. In some instances, cement compositions and associated spacer fluids used in the cementing operation are placed into the wellbore through the bottom hole assembly. Casing drilling enables the well to be drilled and cased without the delays associated with removal of the drill bit and drill string from the wellbore.
A number of different fluids may be used in drilling and casing the wellbore. For instance, a drilling fluid may be pumped down through the drill string (or casing), out through the drill bit, and returned to the surface in the annulus between the drill string and the wellbore wall. The drilling fluid can act to lubricate and cool the drill bit as well as carry drill cuttings back to the surface. Spacer fluids can also be used in these operations. For instance, a spacer fluid may be used to displace drilling fluids from the wellbore before introduction of another fluid, such as a cement composition. Cement compositions may be used to cement the casing in the wellbore. The cement composition may be allowed to set in the annulus between the casing and the wellbore wall, thereby forming an annular sheath of hardened cement (e.g., a cement sheath) that should support and position the pipe string in the wellbore and bond the exterior surface of the pipe string to the walls of the wellbore. While a variety of different fluids have been used with some success in drilling and casing wellbore, improved fluids and techniques for their placement are needed in subterranean operations.